Waiting until the last minute, Rosario Ramos stood in line yesterday to report her $7,000 annual income from selling cosmetics door to door. An illegal immigrant from Mexico, she expected to contribute roughly 10% to the government, which she did last year, and not to qualify for a major tax credit.

“It’s very little, but I have the hope that one day I will have a Social Security card number in the future,” Ms. Ramos said in Spanish.

Experts say it is false to assume that the estimated 10 million illegal immigrants in America do not pay taxes. Many file for the same reason as Ms. Ramos: to establish a good standing with the government. An individual tax identification number provides a legal loophole for illegal immigrants to file tax returns. The Internal Revenue Service created the ITIN in 1996, and it allows individuals who don’t have Social Security numbers to file tax returns. More than 7 million tax identification numbers were issued in 2003, most of them to illegal immigrants, according to the General Accounting Office.

Many illegal immigrants file tax returns in the hope that if the government grants an amnesty, they will have an advantage in gaining legal status. The last amnesty was granted in 1986. President Bush raised the hopes of immigrants when he proposed a temporary worker program in 2004, but it does not look likely to become a reality anytime soon.

Ms. Ramos filed her taxes at a free site in Jackson Heights sponsored by Food-Change, a nonprofit that provides nutrition and financial education. Business was brisk yesterday, with shoe shiners to hotel workers coming in for advice.

A site manager, Oscar Quinonez, said more than 100 tax returns had already been filed there using ITIN numbers. “They come in when they don’t have a Social Security card or they bought a Social Security card,” he said. Many immigrants file using fraudulent Social Security numbers and never benefit from their returns.

Ten blocks down Roosevelt Avenue from the Jackson Heights site is a popular spot to buy counterfeit Social Security cards. For $40, one can be made available within an hour. At the FoodChange site, accountants explained to immigrants, some of whom had been working in America for more than a decade, how even though they were working with illegal documents, they could report their taxes legally with an ITIN number.

Not surprisingly, a major concern for immigrants working illegally is whether there is a chance of deportation or arrest if they report their earnings. The director of income policy at FoodChange, Stephen Lee, said this fear is the greatest obstacle to getting illegal immigrants to file their taxes, even though the IRS cannot share the information with other agencies. The Social Security Administration is not authorized to use the IRS information to help stop fraudulent use of Social Security numbers. “The reality is the IRS cannot share the information with anyone and they don’t,” Mr. Lee said.

Tax and immigration specialists said immigrants can benefit from filing returns, particularly in cases where there is a possibility of gaining legal status.